ABSTRACT Sulfur mustard gas (SM), a vesicating and warfare agent, has been used in many wars since World War I; most recently in Syria. SM rapidly penetrates the eye on contact and causes blindness by injuring corneal tissue- organization and function. Clinically, patients show a pathology termed as Mustard Gas Keratopathy that involves severe ocular inflammation, recurrent epithelial-erosions, epithelial-stromal separation limbal stem cell deficiency, corneal ulceration, haze and neovascularization. MGK pathophysiology is biphasic including acute and delayed-onset, and involves multiple mechanisms. We developed a novel, multimodal, non-steroidal topical ophthalmic drops, Turbo Eye Drop (TED), containing 4 FDA-approved generic drugs with differing mode of action, and stable at ambient temperature. Our pilot studies found that topical TED efficaciously treats acute and delayed-onset MGK in rabbits in vivo and human cornea ex vivo without significant side effects. Our central hypothesis is that topical TED treats acute and delayed-onset MGK in vivo by curbing SM-induced early inflammatory responses, extracellular matrix degradation, and production of excessive pro-fibrotic and pro- angiogenic factors without significant side effects. This project tests two novel hypotheses to establish an efficacious and safe topical therapy for acute and delayed-onset MGK in vivo, using four specific aims: Aim-1 defines TED treatment for acute MGK in vivo by testing the hypothesis that increasing frequency and duration of TED application will potently treat acute MGK and blindness without significant side effects. Aim-2 establishes TED treatment for delayed-onset MGK in vivo by testing the hypothesis that low TED topical dosing for longer duration will effectively cure delayed-onset MGK without issues in rabbits. Aim-3 uncovers mechanisms used by TED in mitigating acute and delayed-onset MGK in vivo and in vitro. Aim-4 secures intellectual property rights, develops regulatory strategies, and advances TED topical ophthalmic drops as an antidote for SM-induced ocular injury towards human application. This will be accomplished using an established SM-vapor rabbit in vivo and human cornea organ culture ex vivo models, GMP-grade TED eye drops, and monitoring eyes in live rabbits in a time-dependent manner with clinical eye exams and diagnostic imaging. The characterization of mechanisms used by TED in mitigating MGK will be studied using corneal tissues collected after euthanasia by measuring integrity of corneal epithelial basement membrane, epithelial-stromal organization, and collagen fibril arrangement using qPCR, ELISAs, immunofluorescence, H&E, and transmission electron microscopy techniques utilizing our published methods. Successful completion of the project will lead to the development of an effective and safe therapy for acute and delayed MGK and medical countermeasure to minimize ocular obliteration caused by the accidental or intentional use of SM in humans, and therefore will have very high impact in field and public safety.